Support VS Code-compatible Copilot hook payloads

cmd/entire/cli/agent/copilotcli/compat.go

@@ -0,0 +1,209 @@
+package copilotcli
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"slices"
+	"time"
+)
+
+// HookHost identifies which host format produced a copilot-compatible hook payload.
+type HookHost string
+
+const (
+	HostUnknown    HookHost = "unknown"
+	HostCopilotCLI HookHost = "copilot-cli"
+	HostVSCode     HookHost = "vscode"
+)
+
+// VS Code hookEventName values (from official VS Code docs).
+// See: https://code.visualstudio.com/docs/copilot/customization/hooks
+const (
+	VSCodeEventSessionStart     = "SessionStart"
+	VSCodeEventUserPromptSubmit = "UserPromptSubmit"
+	VSCodeEventStop             = "Stop"
+	VSCodeEventPreToolUse       = "PreToolUse"
+	VSCodeEventPostToolUse      = "PostToolUse"
+	VSCodeEventPreCompact       = "PreCompact"
+	VSCodeEventSubagentStart    = "SubagentStart"
+	VSCodeEventSubagentStop     = "SubagentStop"
+)
+
+// vsCodeEventToHookNames maps each VS Code hookEventName to the CLI hook name(s)
+// that are allowed to carry that event. "Stop" maps to both agent-stop and
+// session-end because VS Code uses a single Stop event where Copilot CLI
+// distinguishes the two.
+var vsCodeEventToHookNames = map[string][]string{
+	VSCodeEventUserPromptSubmit: {HookNameUserPromptSubmitted},
+	VSCodeEventSessionStart:     {HookNameSessionStart},
+	VSCodeEventStop:             {HookNameAgentStop, HookNameSessionEnd},
+	VSCodeEventSubagentStop:     {HookNameSubagentStop},
+	VSCodeEventPreToolUse:       {HookNamePreToolUse},
+	VSCodeEventPostToolUse:      {HookNamePostToolUse},
+	VSCodeEventPreCompact:       {},
+	VSCodeEventSubagentStart:    {},
+}
+
+type hookEnvelope struct {
+	Host           HookHost
+	SessionID      string
+	Prompt         string
+	TranscriptPath string
+	HookEventName  string
+	Source         string
+	InitialPrompt  string
+	StopReason     string
+	Reason         string
+	Timestamp      time.Time
+}
+
+func parseHookEnvelope(data []byte) (*hookEnvelope, error) {
+	if len(data) == 0 {
+		return nil, errors.New("empty hook input")
+	}
+
+	var raw map[string]json.RawMessage
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return nil, fmt.Errorf("failed to parse hook input: %w", err)
+	}
+
+	env := &hookEnvelope{
+		Host:           detectHookHost(raw),
+		SessionID:      firstString(raw, "sessionId", "session_id"),
+		Prompt:         firstString(raw, "prompt"),
+		TranscriptPath: firstString(raw, "transcriptPath", "transcript_path"),
+		HookEventName:  firstString(raw, "hookEventName"),
+		Source:         firstString(raw, "source"),
+		InitialPrompt:  firstString(raw, "initialPrompt"),
+		StopReason:     firstString(raw, "stopReason"),
+		Reason:         firstString(raw, "reason"),
+	}
+
+	ts, err := parseTimestamp(raw["timestamp"])
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse hook input: %w", err)
+	}
+	env.Timestamp = ts
+
+	if env.Timestamp.IsZero() {
+		env.Timestamp = time.Now()
+	}
+
+	return env, nil
+}
+
+func detectHookHost(raw map[string]json.RawMessage) HookHost {
+	if isJSONString(raw["hookEventName"]) {
+		return HostVSCode
+	}
+	if isJSONString(raw["transcript_path"]) {
+		return HostVSCode
+	}
+	if isJSONString(raw["timestamp"]) {
+		return HostVSCode
+	}
+	if _, ok := raw["transcriptPath"]; ok {
+		return HostCopilotCLI
+	}
+	if isJSONNumber(raw["timestamp"]) {
+		return HostCopilotCLI
+	}
+	return HostUnknown
+}
+
+func firstString(raw map[string]json.RawMessage, keys ...string) string {
+	for _, key := range keys {
+		value, ok := raw[key]
+		if !ok {
+			continue
+		}
+		var s string
+		if err := json.Unmarshal(value, &s); err == nil {
+			return s
+		}
+	}
+	return ""
+}
+
+func parseTimestamp(raw json.RawMessage) (time.Time, error) {
+	if len(raw) == 0 || string(raw) == "null" {
+		return time.Time{}, nil
+	}
+
+	var millis int64
+	if err := json.Unmarshal(raw, &millis); err == nil {
+		if millis == 0 {
+			return time.Time{}, nil // Treat epoch as missing — triggers time.Now() fallback.
+		}
+		return time.UnixMilli(millis), nil
+	}
+
+	var ts string
+	if err := json.Unmarshal(raw, &ts); err != nil {
+		return time.Time{}, fmt.Errorf("unmarshal timestamp string: %w", err)
+	}
+
+	parsed, err := time.Parse(time.RFC3339Nano, ts)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("parse timestamp %q: %w", ts, err)
+	}
+	return parsed, nil
+}
+
+func isJSONString(raw json.RawMessage) bool {
+	if len(raw) == 0 || raw[0] != '"' {
+		return false
+	}
+	var s string
+	return json.Unmarshal(raw, &s) == nil
+}
+
+func isJSONNumber(raw json.RawMessage) bool {
+	if len(raw) == 0 || raw[0] == 'n' {
+		return false
+	}
+	var n int64
+	return json.Unmarshal(raw, &n) == nil
+}
+
+// validateVSCodeEvent checks whether the hookEventName is consistent with the
+// CLI hook subcommand that was invoked. Returns true if the event should be
+// processed, false if it should be silently skipped (mismatch or unknown event).
+func validateVSCodeEvent(env *hookEnvelope, hookName string) bool {
+	hookEventName := env.HookEventName
+	allowedHooks, known := vsCodeEventToHookNames[hookEventName]
+	if !known {
+		return false
+	}
+	if !slices.Contains(allowedHooks, hookName) {
+		return false
+	}
+
+	// VS Code overloads "Stop" for both end-of-turn and terminal session-stop
+	// payloads. Route them by reason to avoid ending sessions on ordinary turns.
+	if hookEventName == VSCodeEventStop {
+		isTerminal := isTerminalVSCodeStop(env)
+		switch hookName {
+		case HookNameAgentStop:
+			return !isTerminal
+		case HookNameSessionEnd:
+			return isTerminal
+		}
+	}
+
+	return true
+}
+
+func isTerminalVSCodeStop(env *hookEnvelope) bool {
+	if env.Reason != "" {
+		return true
+	}
+
+	switch env.StopReason {
+	case "", "end_turn":
+		return false
+	default:
+		return true
+	}
+}

cmd/entire/cli/agent/copilotcli/compat_test.go

@@ -0,0 +1,161 @@
+package copilotcli
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestDetectHookHost(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		raw  string
+		want HookHost
+	}{
+		{
+			name: "copilot cli numeric timestamp",
+			raw:  `{"timestamp":1771480081360,"sessionId":"sess-123","prompt":"hi"}`,
+			want: HostCopilotCLI,
+		},
+		{
+			name: "vscode hook event field",
+			raw:  `{"timestamp":"2026-02-09T10:30:00.000Z","sessionId":"sess-123","hookEventName":"UserPromptSubmit","prompt":"hi"}`,
+			want: HostVSCode,
+		},
+		{
+			name: "vscode transcript_path",
+			raw:  `{"timestamp":1771480081360,"sessionId":"sess-123","transcript_path":"/tmp/transcript.json"}`,
+			want: HostVSCode,
+		},
+		{
+			name: "null hookEventName is not vscode",
+			raw:  `{"timestamp":1771480081360,"sessionId":"sess-123","hookEventName":null}`,
+			want: HostCopilotCLI,
+		},
+		{
+			name: "null transcript_path is not vscode",
+			raw:  `{"timestamp":1771480081360,"sessionId":"sess-123","transcript_path":null}`,
+			want: HostCopilotCLI,
+		},
+		{
+			name: "unknown payload",
+			raw:  `{"sessionId":"sess-123"}`,
+			want: HostUnknown,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			var raw map[string]json.RawMessage
+			if err := json.Unmarshal([]byte(tt.raw), &raw); err != nil {
+				t.Fatalf("unmarshal test fixture: %v", err)
+			}
+
+			if got := detectHookHost(raw); got != tt.want {
+				t.Fatalf("detectHookHost() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestParseTimestamp_NullAndZeroFallBackToNow(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		raw  string
+	}{
+		{name: "null timestamp", raw: `{"timestamp":null,"sessionId":"s"}`},
+		{name: "zero timestamp", raw: `{"timestamp":0,"sessionId":"s"}`},
+		{name: "missing timestamp", raw: `{"sessionId":"s"}`},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			env, err := parseHookEnvelope([]byte(tt.raw))
+			if err != nil {
+				t.Fatalf("parseHookEnvelope() error = %v", err)
+			}
+			if env.Timestamp.IsZero() {
+				t.Fatal("expected time.Now() fallback, got zero time")
+			}
+			if env.Timestamp.Year() < 2025 {
+				t.Fatalf("expected recent timestamp from time.Now(), got %v", env.Timestamp)
+			}
+		})
+	}
+}
+
+func TestDetectHookHost_NullTimestampIsNotCopilotCLI(t *testing.T) {
+	t.Parallel()
+
+	var raw map[string]json.RawMessage
+	if err := json.Unmarshal([]byte(`{"timestamp":null,"sessionId":"s"}`), &raw); err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+
+	if got := detectHookHost(raw); got == HostCopilotCLI {
+		t.Fatalf("null timestamp should not classify as HostCopilotCLI, got %q", got)
+	}
+}
+
+func TestParseHookEnvelope_AcceptsAlternateTranscriptPathAndTimestampFormats(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		raw  string
+		host HookHost
+		path string
+	}{
+		{
+			name: "copilot cli fields",
+			raw:  `{"timestamp":1771480085412,"sessionId":"sess-123","transcriptPath":"/tmp/copilot.jsonl"}`,
+			host: HostCopilotCLI,
+			path: "/tmp/copilot.jsonl",
+		},
+		{
+			name: "vscode fields",
+			raw:  `{"timestamp":"2026-02-09T10:30:00.000Z","sessionId":"sess-123","hookEventName":"Stop","transcript_path":"/tmp/vscode.json"}`,
+			host: HostVSCode,
+			path: "/tmp/vscode.json",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			env, err := parseHookEnvelope([]byte(tt.raw))
+			if err != nil {
+				t.Fatalf("parseHookEnvelope() error = %v", err)
+			}
+			if env.Host != tt.host {
+				t.Fatalf("Host = %q, want %q", env.Host, tt.host)
+			}
+			if env.TranscriptPath != tt.path {
+				t.Fatalf("TranscriptPath = %q, want %q", env.TranscriptPath, tt.path)
+			}
+			if env.Timestamp.IsZero() {
+				t.Fatal("Timestamp should be populated")
+			}
+		})
+	}
+}
+
+func TestParseHookEnvelope_AcceptsSnakeCaseSessionID(t *testing.T) {
+	t.Parallel()
+
+	env, err := parseHookEnvelope([]byte(`{"timestamp":"2026-02-09T10:30:00.000Z","session_id":"sess-456","hookEventName":"UserPromptSubmit","prompt":"hi"}`))
+	if err != nil {
+		t.Fatalf("parseHookEnvelope() error = %v", err)
+	}
+	if env.SessionID != "sess-456" {
+		t.Fatalf("SessionID = %q, want %q", env.SessionID, "sess-456")
+	}
+}